1. Field of the Invention
The present invention relates to a relaxation oscillator, and more particularly to a quadrature phase relaxation oscillator.
2. Description of the Prior Art
Normally speaking, oscillators are common to use in various types of clock generator circuits, but traditional relaxation oscillators with high noise performance cannot be widely utilized in high frequency wired transmission systems or radio frequency circuits. Therefore, inductance-capacitor oscillators (LC oscillators) with low noise performance are more common to use and be applied in high frequency wired transmission systems or radio frequency wireless communication modules as transceivers, but have drawbacks of larger area and narrower frequency tuning range. Quadrature phase relaxation oscillators, compared to the LC oscillators, have smaller areas and wider frequency tuning ranges. However, a well-known quadrature phase relaxation oscillator is achieved by merely changing the capacitor of the source electrode or the loading resistor to modulate the relaxation oscillating frequency of the output signals. Thus, the quadrature phase relaxation oscillators are unable to achieve the tuning range from Mega to Giga Hz order and difficult to be applied in various types of high standard systems for the obvious inferiority of worse phase noise performance.
In summary, it is highly desirable to provide a novel synchronous quadrature phase relaxation oscillator having an ultra-wideband tuning range and a better phase noise performance.